Extractives of Australian Timbers. IV. Castanogenin (Medicagenic Acid) and Bayogenin, C₃₀H₄₈O₅, from Castanospermum australe Cunn. et Fras

Abstract

Castanogenin, the major genin produced on hydrolysis of the saponin of Castanospermum australe Cunn, et Fras. is shown to be identical with medicagenic acid (2β,3β-dihydroxyolean-12-en-23,28-dioic acid). Further proof of several of the structural features of medicagenic acid is given. The minor sapogenin, bayogenin, C₃₀H₄₈O₅, is shown to be 2β,3β,23-trihydroxyolean-12-en-28-oic acid by conversion into the same tetrol as is formed from medicagenic acid and by the formation of a γ-lactone by interaction of the carboxyl function and the 12,13-double bond.